Tunable phenylacetylene hosts

ABSTRACT

Disclosed herein is a class of tunable phenylacetylene compounds as well as compositions and methods for their use as host compounds for ligand binding. In certain examples the hosts report binding events by exhibiting altered spectroscopic properties, such as different fluorescent emission spectra.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application under 35 U.S.C. §121 ofcopending application Ser. No. 11/957,243, filed Dec. 14, 2007, which inturn claims the benefit under 35 U.S.C. §119(e) of the earlier filingdate of U.S. Provisional Application Ser. No. 60/875,055, filed Dec. 14,2006; both of which are incorporated by reference in their entirety.

ACKNOWLEDGMENT OF GOVERNMENT SUPPORT

This invention was made with government support under Grant Nos.CHE-0414175 and CHE-0718242 awarded by the National Science Foundation.The government has certain rights in the invention.

FIELD

Disclosed herein is a class of tunable phenylacetylene compounds as wellas compositions and methods for their use as host compounds for ligandbinding.

BACKGROUND

The synthesis of new molecules designed to bind or sense and report thepresence of a particular substrate is an area of chemistry that isattracting attention. There exists a general lack of ligand-specifichost molecules, such as specific hosts for toxic ions and smallmolecules of interest. There also is a dearth of specific hosts thatreport binding events, for example by exhibiting a spectral shift uponbinding, such as an altered fluorescent response. In fact, structures offluorescent coordination complexes are generally poorly understood,which makes the rational design of functional hosts and sensors achallenging undertaking.

The detection of ionic species, in particular the selective detection ofa particular ionic species in the presence of another is difficult. Thedetection of anionic species is a particular challenge, as anions aredifficult to bind and are generally larger than cations leading to asmaller charge-to-radius ratio.

SUMMARY

Disclosed herein are host or receptor compounds that bind targets ofinterest. In one embodiment the compounds bind ions, such as metal ions.In particular, toxic metal ions, including anions and cations are boundby embodiments of the disclosed host compounds.

In one embodiment the host compounds and salts thereof have the formula

wherein Y represents an optionally substituted aromatic group;

n is 1 or 2;

R is H or lower alkyl;

R¹ is H, lower alkyl or aralkyl;

R² is selected from H, acyl, aralkyl, phosphonyl, —SO₂R³; —(R⁴)C(O)R⁵;—N(R⁶)C(O)OR⁷ and —N(R⁸)C(O)NR⁹R¹⁰;

R³; R⁴; R⁵; R⁶; R⁷; R⁸ R⁹ and R¹⁰ independently are selected from H,lower alkyl, aralkyl and aryl.

Exemplary compounds exhibit shifts in their spectral properties uponligand binding. Accordingly, also disclosed are methods for using thehost compounds to detect targets of interest, including neutral,cationic and anionic targets.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription.

DETAILED DESCRIPTION

The following explanations of terms and methods are provided to betterdescribe the present compounds, compositions and methods, and to guidethose of ordinary skill in the art in the practice of the presentdisclosure. It is also to be understood that the terminology used in thedisclosure is for the purpose of describing particular embodiments andexamples only and is not intended to be limiting.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. Itwill be further understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint.

“Acyl” refers group of the formula RC(O)— wherein R is an organic group.

The term “aliphatic” includes alkyl, alkenyl, alkynyl, halogenated alkyland cycloalkyl groups as described above. A “lower aliphatic” group is abranched or unbranched aliphatic group having from 1 to 10 carbon atoms.

The term “alkyl” refers an aliphatic group that is a branched orunbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such asmethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl,hexyl, heptyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyland the like. A “lower alkyl” group is a saturated branched orunbranched hydrocarbon having from 1 to 10 carbon atoms.

The term “amine” or “amino” refers to a group of the formula —NRR′,where R and R′ can be, independently, hydrogen or an alkyl, alkenyl,alkynyl, aryl, aralkyl, cycloalkyl, halogenated alkyl, orheterocycloalkyl group described above.

The term “amide” refers to the formula —C(O)NRR′, wherein R and R′independently can be a hydrogen, alkyl, alkenyl, alkynyl, aryl, aralkyl,cycloalkyl, halogenated alkyl, or heterocycloalkyl group describedabove.

The term “aralkyl” refers to an alkyl group that is substituted with oneor more aryl groups (described below). A particular example of anaralkyl group is a benzyl group.

The term “aryl” refers to any carbon-based aromatic group including, butnot limited to, benzene, naphthalene, etc. The term “aromatic” alsoincludes “heteroaryl groups,” which are defined as aromatic groups thathave at least one heteroatom incorporated within the ring of thearomatic group. Examples of heteroatoms include, but are not limited to,nitrogen, oxygen, sulfur, and phosphorous. The aryl group can besubstituted with one or more groups including, but not limited to,alkyl, alkynyl, alkenyl, aryl, halide, nitro, amino, ester, ketone,aldehyde, hydroxy, carboxylic acid, or alkoxy, or the aryl group can beunsubstituted.

“Carbonyl” refers to a radical of the formula —C(O)—.Carbonyl-containing groups include any substituent containing acarbon-oxygen double bond (C═O), including acyl groups, amides, carboxygroups, esters, ureas, carbamates, carbonates and ketones and aldehydes,such as substituents based on —COR or —RCHO where R is an aliphatic,heteroaliphatic, alkyl, heteroalkyl, hydroxyl, or a secondary, tertiary,or quaternary amine.

“Carbonate” refers to a group of the formula —OC(O)O—. Likewise, as usedherein the term “carbamate” refers to a group of the formula—OC(O)N(R)—, wherein R is H, or an aliphatic group, such as a loweralkyl group or an aralkyl group.

“Carboxyl” refers to a —COOH radical. Substituted carboxyl refers to—COOR where R is aliphatic, heteroaliphatic, alkyl, heteroalkyl, or acarboxylic acid or ester.

“Optional” or “optionally” means that the subsequently described eventor circumstance can but need not occur, and that the descriptionincludes instances where said event or circumstance occurs and instanceswhere it does not. Optionally substituted groups, such as “substitutedalkyl,” refers to groups, such as an alkyl group, having from 1-5substituents, typically from 1-3 substituents, selected from alkoxy,optionally substituted alkoxy, acyl, acylamino, acyloxy, amino,aminoacyl, aminoacyloxy, aryl, carboxyalkyl, optionally substitutedcycloalkyl, optionally substituted cycloalkenyl, optionally substitutedheteroaryl, optionally substituted heterocyclyl, hydroxy, thiol andthioalkoxy.

The term “phosphoryl” refers to moieties of the formula —P(O)OR—,wherein R may be H, an aliphatic or aromatic moiety, a cation or a lonepair of electrons. Phosphoryl moieties may be further substituted toform phosphoramidates, phosphates and phosphonates.

The term “sulfonyl” refers to the radical —SO₂—. The sulfonyl group canbe further substituted with a variety of groups to form, for example,sulfonic acids, sulfonamides, sulfonate esters and sulfones.

Protected derivatives of the disclosed compound also are contemplated. Avariety of suitable protecting groups for use with the disclosedcompounds are disclosed in Greene and Wuts Protective Groups in OrganicSynthesis; 3rd Ed.; John Wiley & Sons, New York, 1999.

It is understood that substituents and substitution patterns of thecompounds described herein can be selected by one of ordinary skill inthe art to provide compounds that are chemically stable and that can bereadily synthesized by techniques known in the art and further by themethods set forth in this disclosure.

The disclosed host compounds are useful, inter alia, as ion bindingcompounds. By way of example, specific anions bound by the disclosedcompounds include, but are not limited to, toxic metal anions, halideanions, carboxylates, phosphates, sulfates, oxalates, terephthalates,phospholipids, nucleotides, oligonucleotides, DNA, RNA, anionicpolyoxometalates, or oxoanions such as pertechnetate.

The structural formulas provided herein include salts of the illustratedcompounds. Such salts can be formed when disclosed host compoundspossess at least one basic group that can form acid-base salts withacids. Examples of basic groups present in exemplary disclosed hostcompounds include amino groups or imino groups. Examples of inorganicacids that can form salts with such basic groups include, but are notlimited to, mineral acids such as hydrochloric acid, hydrobromic acid,sulfuric acid or phosphoric acid. Basic groups also can form salts withorganic carboxylic acids, sulfonic acids, sulfo acids or phospho acidsor N-substituted sulfamic acid, for example acetic acid, propionic acid,glycolic acid, succinic acid, maleic acid, hydroxymaleic acid,methylmaleic acid, fumaric acid, malic acid, tartaric acid, gluconicacid, glucaric acid, glucuronic acid, citric acid, benzoic acid,cinnamic acid, mandelic acid, salicylic acid, 4-aminosalicylic acid,2-phenoxybenzoic acid, 2-acetoxybenzoic acid, embonic acid, nicotinicacid or isonicotinic acid, and, in addition, with amino acids, forexample with α-amino acids, and also with methanesulfonic acid,ethanesulfonic acid, 2-hydroxymethanesulfonic acid,ethane-1,2-disulfonic acid, benzenedisulfonic acid,4-methylbenzenesulfonic acid, naphthalene-2-sulfonic acid, 2- or3-phosphoglycerate, glucose-6-phosphate or N-cyclohexylsulfamic acid(with formation of the cyclamates) or with other acidic organiccompounds, such as ascorbic acid.

Similarly, salts can be formed when disclosed host compounds possess atleast one acidic group that can form acid-base salts with bases.Examples of acidic groups present in exemplary disclosed host compoundsinclude carboxylic acid moieties and sulfonamide groups. Compounds thatinclude at least one acidic group can form acid-base salts with aninorganic or organic base. Examples of salts formed from inorganic basesinclude salts of the presently disclosed compounds with alkali metalssuch as potassium and sodium, alkaline earth metals, including calciumand magnesium and the like. Similarly, salts of acidic compounds with anorganic base, such as an amine (as used herein terms that refer toamines should be understood to include their conjugate acids unless thecontext clearly indicates that the free amine is intended) arecontemplated, including salts formed with basic amino acids, aliphaticamines, heterocyclic amines, aromatic amines, pyridines, guanidines andamidines. In addition, quaternary ammonium counterions also can be used.

Additionally, the structural formulas herein are intended to cover,where applicable, solvated as well as unsolvated forms of the compounds.“Solvate” refers to a compound physically associated with one or moresolvent molecules. This physical association involves varying degrees ofionic and covalent bonding, including by way of example covalent adductsand hydrogen bonded solvates. In certain instances the solvate will becapable of isolation, for example when one or more solvent molecules areincorporated in the crystal lattice of the crystalline solid. “Solvate”encompasses both solution-phase and isolable solvates. Representativesolvates include ethanol associated compounds, methanol associatedcompounds, and the like. “Hydrate” is a solvate wherein the solventmolecule(s) is/are H₂O. Solvate complexes may be described in shorthandform for example as (1.H₂O)₂, which refers to a hydrate, morespecifically a 2+2 complex of compound 1 with water.

Compounds disclosed herein can be crystallized and can be provided in asingle crystalline form or as a combination of different crystalpolymorphs. As such, the compounds can be provided in one or morephysical form, such as different crystal forms, crystalline, liquidcrystalline or non-crystalline (amorphous) forms. Such differentphysical forms of the compounds can be prepared using, for exampledifferent solvents or different mixtures of solvents forrecrystallization. Alternatively or additionally, different polymorphscan be prepared, for example, by performing recrystallization atdifferent temperatures and/or by altering cooling rates duringrecrystallization. The presence of polymorphs can be determined by X-raycrystallography, or in some cases by another spectroscopic technique,such as solid phase NMR spectroscopy, IR spectroscopy, or bydifferential scanning calorimetry.

In one embodiment, the disclosed host compounds have the formula

wherein Y represents an optionally substituted aromatic group;

n is 1 or 2;

R is H or lower alkyl;

R¹ is H, lower alkyl or aralkyl;

R² is selected from H, acyl, aralkyl, phosphonyl, —SO₂R³; —(R⁴)C(O)R⁵;—N(R⁶)C(O)OR⁷ and —N(R⁸)C(O)NR⁹R¹⁰;

R³; R⁴; R⁵; R⁶; R⁷; R⁸ R⁹ and R¹⁰ independently are selected from H,lower alkyl, aralkyl and aryl.

In embodiments wherein n is 1, the disclosed host compounds can berepresented by the formula

With reference to the generic formulas above, a guest molecule can bindin the cavity created between the aromatic group “Y” and the functionalgroups appended to the aniline nitrogens “R¹ and R²”.

With continued reference to the general formula above, such compoundscan be cyclized, for example, by covalently linking an R¹ or R² group toanother. Thus, macrocyclic compounds can be formed by linking an R¹ orR² group to another R¹ or R² group on a different aniline nitrogen.

With continued reference to the formula above, the R group can beselected for several purposes. Typically, R is selected to tune ortailor the electronics of the ring by selecting an electron donating orelectron withdrawing and/or conjugated group. In other examples, R isselected for detection purposes, or, for instance, to affect thesolubility of the overall molecule. Suitable R groups include, withoutlimitation those listed in Table 1.

Hammett constant Structure/name (σ_(para)) —H 0.00 —OCH₃ −0.27 —CH₃−0.04 —CH₂CH₃ −0.05 —C(CH₃)₃ —F 0.06 —Cl 0.23 —Br 0.23 —I 0.18 —CF₃ 0.54—OCF₃ —NO₂ 0.78

—N₃ —CN 0.66 —OH −0.37 —NH₂ −0.66

−0.83

0.45 —SO₃ ⁻ 0.09

The group “Y” can be any aromatic group, but typically Y comprises aheteroaromatic group. For example, in one embodiment, the group “Y”employed was a pyridyl group. Additional exemplary Y groups include,without limitation, bipyridyl, pyridinyl, pyrazinyl, pyrimidinyl,pyrrole, imidazole, triazole, thiophene, thiazole, furyl and oxazolylgroups. By way of example, such Y groups can be selected from

In other embodiments, Y is selected from, without limitation, thefollowing hetero aromatic groups

Other appropriate Y groups can be identified by those of skill in theart using the guidance provided by the present disclosure and byconsidering factors such as: the ring topology, bond angles, geometry ofcoordination to the guest, and number of available hydrogen bonds.

In one embodiment, the disclosed host compounds have the structure:

wherein R is H, aliphatic, such as lower alkyl (including optionallysubstituted lower alkyl), aralkyl, aryl, sulfonyl, phosphonyl,phosphate, sulfate, —XC(O)OR⁶ and —XC(O)NR⁷R⁸; wherein X is optional andif present is selected from the group consisting of —O—, —N(R⁹)— or —S—;R⁶ is selected from lower alkyl, aralkyl and aryl; and R⁷, R⁸ and R⁹independently are selected from H, lower alkyl, aralkyl and aryl.

In one embodiment, Y is a hydrogen bond acceptor and/or donor. Forexample when Y is pyridyl, it is a hydrogen bond acceptor at high(basic) pH and a hydrogen bond donor when it is in its conjugate acidform at low pH.

In one embodiment the disclosed host compounds have the structure:

wherein X is selected from halogen, —OR¹¹, nitro, sulfonyl, phosphonyl,phosphate, sulfate, or optionally substituted lower alkyl;

and R¹¹ is H, acyl or optionally substituted lower alkyl. When Xincludes an optionally substituted lower alkyl moiety, optionalsubstitutions include, without limitation hydroxy and sulfide moieties.

Particular examples of sulfonamide host compounds can be represented bythe formula

wherein R is selected from —OR, —SR, —Me, halo, such as —Br, and —NO₂,and wherein R′ is, for each occurrence selected from H, lower alkyl andacyl. With reference to such sulfonamide compounds, they include acidicNH groups, which are good hydrogen bond donors.

Particular examples of such sulfonamide compounds have the formula

Additional embodiments include urea compounds, such as those of theformula:

wherein R is lower alkyl and X is H, halogen, lower alkyl, phosphonyl,phosphate, sulfonyl or sulfate; and R¹¹ is H, acyl or optionallysubstituted lower alkyl.

Other urea compounds have the formula

wherein R¹ is H or optionally substituted lower alkyl, such as methyl,t-butyl, octyl and the like. In one aspect, certain urea compounds canbe represented by the formula

One such compound has the formula

A second such urea compound has the formula

In one aspect, certain host compounds are represented by the formula

wherein X is O or S;

R is H, acyl, aralkyl or lower alkyl; and R′ is H or lower alkyl, suchas t-butyl. Examples of such compounds can be represented by the formula

When X is O, the host compounds are particularly useful for bindingoxophilic ions, such as calcium. Other host compounds having the formulaabove, wherein X is S have been designed to bind thiophilic metals.Examples of such compounds can be represented by the formula:

wherein R is H, acyl, aralkyl or lower alkyl; and R′ is H, aliphatic,such as lower alkyl, aralkyl, aryl, sulfonyl, phosphonyl, phosphate,sulfate, —XC(O)OR⁶ or —XC(O)NR⁷R⁸; wherein X is optional and if presentis selected from the group consisting of —O—, —N(R⁹)— or —S—; R⁶ isselected from lower alkyl, aralkyl and aryl; and R⁷, R⁸ and R⁹independently are selected from H, lower alkyl, aralkyl and aryl.Particular examples of such compounds also can be represented by theformula

wherein R is H, acyl, aralkyl or lower alkyl.

Additional compounds useful for binding thiophilic metals include thoseof the formula

wherein X comprises an alkyl sulfide moiety.

Also disclosed herein are methods for making the disclosed receptorcompounds as well as intermediates for preparing the receptors. One typeof versatile intermediate employed in the synthesis of exemplaryreceptor compounds disclosed herein is represented by the formula

wherein R is H, lower alkyl, aralkyl or the like. Such compounds can beused to assemble (typically by an organometallic coupling reaction, suchas a Sonogashira coupling) compounds of the formula

wherein X represents an aniline nitrogen, which optionally may besubstituted. The aniline nitrogens can be converted into any one of manyheteroatomic functional groups, including amides, sulfonamides, ureas,imines, and the like using standard synthetic techniques known to thoseof skill in the art of synthetic organic chemistry. The choice of groupis dictated by several factors, including: optimizing guestinteractions, changing the size of the binding cavity, preorganizing thebinding cavity (by cyclization, for instance). Such factors arerecognized and can be adjusted by those of skill in the art.

The disclosed host compounds are useful for binding and/or detectingligands, in particular ionic ligands, including cationic and anionicligands. The ligands may be inorganic or organic, but generally areinorganic. Typically, for binding anionic ligands, host compounds areprotonated. Particular examples of anionic ligands bound and/orrecognized by the disclosed host compounds include, without limitationsulfate, hydrogen sulfate, perchlorate or nitrate. Exemplary hostcompounds exhibit ligand binding selectivity or recognition. The hostcompounds may exhibit selectivity in binding of the ligand or reportingof a ligand's presence. For example, a spectral property of a hostcompound, such as fluorescence, may shift upon binding certain ligands,but not others. Examples of the disclosed host compounds have beendesigned to bind to salts containing particular metals, particularlytoxic metals, including without limitation Pb, As, Zn, U, Ca, Cd and Hg.

It has been demonstrated for exemplary compounds disclosed herein thatthe spectral properties, such as the UV-Vis spectra shift noticeablyupon binding of different guests. For example, the extended conjugationinherent in 2,6-bis(2-anilinoethynyl)pyridines derivatives producesdistinct emission properties that will be used to monitor interactionswith guest molecules. Exemplary compounds can distinguish betweendifferent anionic guests such as between Cl⁻, which induces a shift inthe UV-vis spectra of certain compounds, and Br⁻, which does not inducesuch shifts. This discriminatory ability is most marked when thereceptor is protonated. This indicates that these specific receptors candiscriminate between different guests and are pH sensitive and can betailored for use in solutions of specific acidity.

Reference will now be made in detail to the presently preferredembodiments of the disclosed compounds, compositions and methods.

EXAMPLES

The following examples are provided to illustrate certain particularfeatures and/or embodiments. These examples should not be construed tolimit the invention to the particular features or embodiments described.

Example 1

This example describes general materials and methods used in thesynthesis and characterization of exemplary host compounds. All solventswere dried over 3 Å molecular sieves unless otherwise stated. THF, Et₃N,and CH₂Cl₂ were respectively distilled from potassium metal and CaH₂prior to use. All other materials were obtained from TCI-America,Sigma-Aldrich, Acros and Strem and used as received. ¹H and ¹³C NMRspectra were recorded using a Varian Inova 300 (¹H 299.95 MHz, ¹³C 75.43MHz) or Inova 500 (¹H 500.10 MHz, ¹³C 125.75 MHz) spectrometer. Chemicalshifts (δ) expressed as ppm downfield from tetramethylsilane usingeither the residual solvent peak as an internal standard (CDCl₃ ¹H: 7.27ppm) or using CDCl₃ spiked with 1% trimethylsilane for the ¹H NMRspectra. For the ¹³C NMR spectra the middle CDCl₃ peak (δ 77.00 ppm) wasused as the internal standard. Signal patterns are indicated as b,broad; s, singlet; d, doublet; t, triplet; m, multiplet. Couplingconstants (J) are given in hertz. UV-Vis spectra were recorded using aHewlett-Packard 8453 spectrophotometer and extinction coefficients areexpressed in M⁻¹ cm⁻¹. Mass spectra were recorded using an Agilent 1100Series LC/MSD. Emission spectra were recorded on a Hitachi F-4500fluorescence spectrophotometer. Melting points were determined with aMeltemp II apparatus or a TA Instruments DSC 2920 Modulated DSC. Columnchromatography was performed on Whatman reagent grade silica gel(230-400 mesh). Rotary chromatography was performed on a HarrisonResearch Chromatotron model 7924T with EM-Science 60PF₂₅₄ silica gel.Precoated silica gel plates (Sorbent Technology, UV₂₅₄, 200 μm, 5×20 cm)were used for analytical thin-layer chromatography.

General Sulfonamide Synthesis: A general synthesis of sulfonamidesfollowed the scheme:

A solution of arene 3 (1 equiv) and sulfonyl chloride (5 equiv) inpyridine (8-15 mM) was stirred for 3 hours under an N₂ environment.Following concentration in vacuo, the crude oil was filtered through a2.5 cm silica plug and then chromatographed on silica gel.

The synthesis of several exemplary sulfonamides by the general method isillustrated by the scheme:

General salt preparation: A 10 mM stock solution of sulfonamide receptordissolved in CDCl₃ with 1% TMS that had been passed through basicalumina and stored over 3 Å molecular sieves was prepared. With a 9 inchpipet and 10 ml pipet bulb HCl gas is passed through the sulfonamidesolution 20 times. The resulting bright yellow solution is diluted tothe original volume and an appropriate aliquot is removed for study.

Crystal growth conditions: Sulfonamide receptors were dissolved in a10×75 mm test tube with EtOAc to a concentration >10 mM (for halidesalts HX gas was passed through the EtOAc solution of receptor).Alternatively, 1 drop of concentrated HX is added and the resultingyellow solution is thoroughly mixed). Hexanes cooled to 0° C. werelayered on top of receptor solutions and set aside. After 3 dayscolorless (neutral receptor complex) or yellow (protonated receptorcomplex) single crystals were harvested for X-ray diffraction studies.

Single Crystal X-ray Diffraction: X-Ray diffraction data for (1.H₂O)₂,(2.H₂O)₂, (H2⁺.Cl⁻)₂, (H1⁺.Cl⁻).(1.H₂O) and (H1⁺.Br⁻)₂ were collected ona Bruker SMART APEX diffractometer using MoK_(α) radiation (δ=0.7107 Å).Data were corrected for absorption using the SADABS v2.02 areaabsorption correction program. The structures were solved by directmethods and refined based on |F|². All non-hydrogen atoms were refinedwith anisotropic displacement parameters. Hydrogen atoms in theinvestigated structures were found from the residual density maps andrefined with isotropic thermal parameters except those in terminal t-Bugroups in (H2⁺.Cl⁻)₂, (H1⁺.Cl⁻).(1.H₂O) and (H1⁺.Br⁻)₂, which wereplaced in calculated positions and refined in a rigid group model withisotropic thermal parameters U(H)=1.5 Ueq (C). One of the H atoms at thebridging solvent molecule in (1.H₂O)₂ is disordered over two positionsin a 1:1 ratio. The O atoms of the bridging water molecule and the Clatom in (H1⁺.Cl⁻).(1H₂O) are disordered over two positions correspondingto opposite orientations of the dimeric units. These O and Cl atoms wererefined in the same positions with occupation factors μ=½. The H atomsattached to the O atom in the bridging water molecules were not foundfrom the F-map. All calculations were performed with the SHELXTL v.6.1program package.

Example 2

This example describes the synthesis of sulfonamide compound 1 via thegeneral synthesis set forth above.

Arene 3 (150 mg, 0.36 mmol) was reacted with p-toluenesulfonyl chlorideaccording to General Preparation for Sulfonamides (above). Purificationby chromatography (1:1 hexanes:EtOAc) afforded (1.H₂O)₂ (249 mg, 95%) asa pale yellow solid. Recrystallization by diffusion (hexanes:EtOAc)afforded colorless crystals. Mp: 133-135° C. ¹H NMR (300 MHz, CDCl₃): δ7.85-7.71 (m, 5H), 7.52-7.43 (m, 6H), 7.35 (dd, J=8.5, 2.3 Hz, 2H), 7.15(d, J=8.5 Hz, 4H), 2.34 (s, 6H), 1.26 (s, 18H). ¹³C NMR (75 MHz, CDCl₃):δ 147.53, 143.73, 142.85, 136.93, 136.49, 135.84, 129.54 (2C), 127.89,127.25, 126.29, 120.52, 112.89, 93.20, 85.56, 34.29, 31.03, 21.45.UV-Vis (CH₂Cl₂): λ_(max) (ε) 234 (58,000), 287 (31,000), 330 (27,600)nm. Fluorescent emission ([(1.H₂O)₂]≦0.057 mM in CHCl₃; 354 nmexcitation): λ_(max) 388 nm. IR (neat): v 3266, 2961, 2899, 2877, 2213,1555, 1156 cm⁻¹. MS (CI pos) m/z (%): 732 (M⁺2, 21), 731 (MH⁺, 56), 730(M⁺, 100); C₄₃H₄₃N₃O₄S₂ (729.95).

Example 3

This example describes the synthesis of sulfonamide compound 2 via thegeneral synthesis set forth above.

Arene 3 (150 mg, 0.36 mmol) was reacted with p-nitrobenzenesulfonylchloride according to General Preparation for Sulfonamides (above).Purification by chromatography (20:1 CH₂Cl₂:EtOAc) afforded (2.H₂O)₂(285 mg, 93%) as a pale yellow solid. Recrystallization by diffusion(pentane:CHCl₃ or hexanes:EtOAc) afforded pale yellow crystals. Mp:136-139° C. ¹H NMR (300 MHz, CDCl₃): δ 8.15 (d, J=8.7 Hz, 4H), 8.03 (d,J=8.7 Hz, 4H), 7.74 (t, J=7.8 Hz, 1H), 7.55 (d, J=8.7 Hz, 2H), 7.48-7.37(m, 6H), 1.29 (s, 18H). ¹³C NMR (75 MHz, CDCl₃): δ 150.10, 149.33,145.32, 142.68, 137.20, 134.63, 129.82, 128.68, 128.28, 126.31, 124.12,123.31, 114.59, 92.68, 85.71, 34.51, 31.05. UV-Vis (CH₂Cl₂): λ_(max) (ε)242 (56,200), 285 (35,500), 319 (23,000) nm. Fluorescent emission([(2.H₂O)₂]≦0.057 mM in CHCl₃; 364 nm excitation): λ_(max) 428 nm. IR(neat): v 3271, 2964, 2869, 2213, 1348, 1171 cm⁻¹. MS (CI pos) m/z (%):794 (M⁺+2, 24), 793 (MH⁺, 53), 792 (M⁺, 100), 608 (17), 607 (44);C₄₁H₃₇N₅O₈S₂ (791.89).

Example 4

This example describes the synthesis of the para-methoxy analog ofcompounds 1 and 2. Arene 3 (110 mg, 0.26 mmol) was reacted withp-methoxybenzenesulfonyl chloride according to General Preparation forSulfonamides (above). Purification by chromatography (20:1 CH₂Cl₂:EtOAc)afforded (pMeO.H₂O)₂ (185 mg, 93%) as a white crystalline solid.Recrystallization by diffusion (hexanes:CH₂Cl₂) afforded colorlesscrystals. Mp: 141-143° C. ¹H NMR (300 MHz, CDCl₃): δ 7.77 (d, J=9 Hz,4H), 7.76 (t, J=9 Hz, 1H), 7.53-7.45 (m, 5H), 7.37 (dd, J=9, 3 Hz, 2H),6.84 (d, J=9 Hz, 4H), 3.77 (s, 6H), 1.28 (s, 18H). ¹³C NMR (75 MHz,CDCl₃): δ 163.06, 147.62, 142.93, 136.75, 135.70, 130.85, 129.60,129.43, 127.85, 126.44, 120.64, 114.09, 113.02, 93.28, 85.33, 55.45,34.31, 31.03. UV-Vis (CH₂Cl₂): λ_(max) (ε) 239 (71,700), 292 (30,200),343 (23,000) nm. Fluorescent emission ([(pMeO.H₂O)₂]≦0.05 mM in CHCl₃;353 nm excitation): λ_(max) 389 nm. IR (neat): v 3248, 2962, 2902, 2870,2214, 1498, 1161 cm⁻¹. MS (CI pos) m/z (%): 764 (M⁺+2, 22), 763 (MH⁺,49), 762 (M⁺, 100); C₄₃H₄₃N₃O₆S₂ (761.95).

Example 5

This example describes the characterization of the solid state andsolution phase ion binding properties of exemplary host moleculesdisclosed herein. Colorless single crystals of compounds 1 and 2suitable for X-ray diffraction were grown by layering hexane onto ethylacetate solutions of each receptor. As suggested from the ¹H NMRspectroscopic data, complexes (1.H₂O)₂ and (2.H₂O)₂ both crystallize asdimers in space group P-1 with two receptor molecules and two watermolecules per unit cell; consequently, each dimer has crystallographicinversion symmetry. A prominent feature of each crystal structure is thepresence of two hydrogen bonding water molecules stitching the receptordimers together. Both pyridine nitrogens accept hydrogen bonds from adifferent water molecule [2.797(4)-2.804(2) Å, O—H . . . N angles172(4)-175(3)°], while one water-water hydrogen bond is present[2.917(5)-3.006(7) Å, O—H . . . O angles 164(4)-178(6)°]. All of theN-substituted sulfonamides adopt the energetically most-favored‘staggered’ conformation, and both sulfonamide protons on each receptordonate a hydrogen bond to a different water molecule [2.855(4)-2.860(3)Å, 157(2)-164(3)° and 3.028(4)-3.039(3) Å, 158(2)-164(3)°] such that the2+2 dimer structure is held together by four sulfonamide-water hydrogenbonds, two pyridine-water hydrogen bonds, one water-water hydrogen bondand two π-stacking interactions between receptors ranging from 3.42-3.44Å.

The dimerization of receptor 1 was further investigated in CDCl₃solutions. Receptor 1 was dissolved in water-saturated CDCl₃ to aconcentration of 197 mM. Monitoring the sulfonamide N—H and water ¹H NMRresonances following a series of dilutions resulted in data that couldbe fit to a 1:1 dimerization with the non-linear regression curvefitting software WinEQNMR. In CDCl₃ solutions receptor 1 is shown todimerize with a modest K_(dim)=42 M⁻¹. Supporting evidence ofdimerization in CDCl₃ solutions resulted from the NOE observed betweenthe protons on the guest water molecules and the sulfonamide protons ofthe receptor. Receptor 1 exhibits a propensity to crystallize as a dimerwith H₂O even in the presence of other potential neutral guest moleculesand in solvents dried over 3 Å molecular sieves.

Receptor molecules 1 and 2 both alter guest selectivity by simplechanges in the protonation state of the receptors. By protonating thepyridine nitrogen of receptors 1 and 2, the anion binding capacity ofthese receptors is activated. The halide binding properties of H1⁺ havebeen investigated in the solid state: single crystals of the chlorideand bromide complexes are prepared by dissolving receptor 1 or 2 inethyl acetate and bubbling HCl or HBr gas through the solution.Crystallization is induced by layering hexanes onto the yellow ethylacetate solutions. Strikingly, the single crystal structures of theH2⁺.Cl⁺ and H1⁺.Br⁻ complexes revealed nearly isostructural dimers tothose observed for the neutral (1.H₂O)₂ and (2.H₂O)₂ water dimers. Inthe solid state the (H2⁺.Cl⁻)₂ and (H1⁺.Br⁻)₂ dimers (FIG. 2) are heldtogether by four sulfonamide hydrogen bonds [3.156(2)-3.229(2) Å, N—H .. . Cl angles 151(2)-171(3)°; 3.338(5)-3.440(6) Å, N—H . . . Br angles136(4)-168(4)°], two pyridinium N—H hydrogen bonds to the anions[3.022(2) Å, 175(3)° for (H2⁺.Cl⁻)₂ and 3.127(6) Å, 173(4)° for(H1⁺.Br⁻)₂], two C_(aryl)—H . . . X hydrogen bonds (3.69-3.90 Å), andtwo π-stacking interactions between receptors (3.49 Å for (H2⁺.Cl⁻)₂ and3.61 Å for (H⁺.Br⁻)₂. The numerous hydrogen bonds and uniquedimerization bring the negatively charged halides into close proximitywith halide-halide distances of 3.92 Å for (H2⁺.Cl⁻)₂ and 4.08 Å for(H1⁺.Br⁻)₂.

CAChe semi-empirical calculations of the2,6-bis(2-anilino-ethynyl)pyridine receptors suggested that largerpolyatomic anions would not fit within the binding pocket of thereceptor. As predicted, the single crystal X-ray structure of the HBF₄salt (H1⁺.BF₄ ⁻) reveals that the binding pocket is too small toaccommodate the interaction of the large BF₄ ⁻ guest with eithersulfonamide proton. Dilution experiments of H1⁺.BF₄ ⁻ revealed minimalchange in the ¹H NMR spectrum upon addition with CDCl₃, indicatingnegligible dimerization in solution as predicted by the receptorconformation observed in the crystal structure. However, titrations ofH1⁺.BF₄ ⁻ with tetra-n-butylammonium halide salts do indicate anionbinding occurs in solution between the receptor and halides.Furthermore, the concentration dependence observed in the ¹H NMRspectrum upon dilution of (H1⁺.Cl⁻)₂ in CDCl₃ indicates the presence ofa receptor/halide dimer in solution. A supersaturated solution of(H1⁺.Cl⁻)₂ (60 mM) was obtained by passing HCl gas through a CDCl₃solution of neutral receptor 1. Plotting the changes in chemical shiftupon dilution and subsequent fitting of this data to a 1:1 dimerizationmodel with the non-linear least squares regression program WinEQNMRresulted in a K_(dim)=250 M⁻¹ in CDCl₃.

Further evidence of dimerization was obtained by mixing a 1:1 ratio ofreceptor 1 and a p-methoxyphenyl sulfonamide derivative (synthesisdescribed in Example 4 above). In an equimolar mixture of the tworeceptors, the resulting ¹H NMR signals are shifted from the signalsobserved for either of the analogous homodimers prepared in the same wayat the same concentration. Briefly, the equimolar mixtures of thesereceptors were prepared at 10 mM in CDCl₃ as follows:[1.H₂O].[pMeO.H₂O]. 1.H₂O (3.650 mg, 0.00488 mmol) and pMeO.H₂O (3.740mg, 0.00480 mmol) were dissolved in seperate portions of CDCl₃ with 1%TMS (1 mL) passed through basic alumina and dried with 3 Å molecularsieves. Aliquots (400 μL) from each solution were transfered to an NMRtube via syringe and thoroughly mixed. ¹H NMR spectra were recorded on aVarian 300 MHz spectrometer. Proton signals were referenced to the 1%TMS included in the CDCl₁₃. ¹H NMR (300 MHz, CDCl₃): δ 7.81-7.73 (m,10H), 7.52-7.44 (m, 12H), 7.38-7.33 (m, 8H), 7.18 (d, J=9 Hz, 4H), 6.85(d, J=9 Hz, 6H), 7.18 (d, J=6 Hz, 3H) 2.29 (s, 6H), 1.26 (s, 18H).

By comparison, 10 mM stock solutions of (H1⁺.Cl⁻)₂ had the data: ¹H NMR(300 MHz, CDCl₃): δ 9.51 (b, 2H), 8.40 (b, 1H), 8.13 (d, J=6 Hz, 4H),8.00-7.75 (b, 4H), 7.48-7.41 (m, 6H), 7.18 (d, J=6 Hz, 3H) 2.29 (s, 6H),1.26 (s, 18H). 10 mM stock solutions of (HpMeO⁺.Cl⁻)₂ had the data: ¹HNMR (300 MHz, CDCl₃): δ 9.36 (b, 2H), 8.31 (t, 1H), 8.17 (d, J=9 Hz,4H), 7.72 (d, J=9 Hz, 4H), 7.40 (m, 6H), 6.86 (d, J=9 Hz, 4H) 3.75 (s,6H), 1.26 (s, 18H).

This result suggests that both homodimers and a third species—theheterodimer—are present in solution, but equilibrating quickly on theNMR timescale. From all of these experiments it is evident thatdimerization of both the neutral and protonated forms of2,6-bis(2-anilinoethynyl)pyridine receptors occurs both in the solidstate and in solution.

Remarkably, a different type of “heterodimer” (H1⁺.Cl⁻).(1.H₂O) was alsocrystallized in the presence of concentrated HCl with one water and onechloride in the binding pocket. Briefly, the heterodimer[H1⁺.Cl⁻].[HpMeO⁺.Cl⁻] was prepared as follows: The stock solutions fromthe preparation of [1.H₂O].[pMeO.H₂O] (above) were combined andprotonated with HCl gas (see above, General salt preparation). ¹H NMRspectra were recorded on a Varian 300 MHz spectrometer. Proton signalswere referenced to the 1% TMS included in the CDCl₃. ¹H NMR (300 MHz,CDCl₃): δ 9.49 (s, 2H), 9.44 (s, 2H), 8.30 (b, 2H), 8.18 (d, J=9 Hz,4H), 8.12 (d, J=9 Hz, 4H), 7.71 (d, J=6 Hz, 4H) 7.46 (m, 12H), 7.17 (d,J=6 Hz, 4H), 6.85 (d, J=6 Hz, 4H), 3.73 (s, 6H), 2.27 (s, 6H), 1.25 (s,36H). The resultant heterodimer contains one protonated receptor thatbinds a chloride anion while the other receptor in the dimer is neutraland bound to a water molecule. Water and chloride are freelyexchangeable in this binding pocket and provide intermediate structuralfeatures to the H₂O and halide dimers. Analogous to the other dimerspresented, the heterodimer is stabilized by π-stacking interactionsbetween the two receptors (3.43 Å) and a series of seven guest assistedhydrogen bonds. Each guest molecule—water and chloride—accepts twosulfonamide N—H hydrogen bonds (3.157(3)-3.181(3) Å, N—H . . . X angles158(3)-167(3)°) and additionally forms a helical hydrogen bondingpattern running between the pyridinium, chloride, water and pyridineheteroatoms (2.926(3)-3.10 Å, 164(3)-176(4)°). Two C_(aryl)—H.Clhydrogen bonds (3.76-3.93 Å) also stabilize the dimer.

Example 6

This example describes the synthesis of the compound

via the General Preparation for Sulfonamides described above. Briefly,arene 3 (100 mg, 0.24 mmol) was reacted with p-bromobenzenesulfonylchloride. Purification by chromatography (2.5:1 hexanes:EtOAc) followedby recrystallization by diffusion (hexanes:EtOAc) afforded 10c (183 mg,89%) as colorless crystals. Mp: 152-154° C. ¹H NMR (300 MHz, CDCl₃): δ8.00 (br s, 2H), 7.82-7.71 (m, 5H), 7.53-7.37 (m, 10H), 1.29 (s, 18H).¹³C NMR (75 MHz, CDCl₃): δ 148.25, 142.72, 138.65, 137.16, 135.52,132.22, 129.59, 128.88, 128.18, 127.96, 126.19, 121.56, 113.46, 92.97,85.89, 34.43, 31.08. Fluorescence emission ([10c]≦5.7×10⁻⁵ M in CHCl₃;308 nm excitation): λ_(max) 381 nm. MS (CI pos) m/z (%): 863 (M⁺+6, 24),862 (M⁺+5, 61), 861 (M⁺+4, 42), 860 (M⁺+3, 100), 859 (M⁺+2, 21), 858(MH⁺); C₄₁H₃₇Br₂N₃O₄S₂ (857.06).

Example 7

This example describes the synthesis of the compound

Phenyl isocyanate (303 mg, 2.5 mmol) was added to a solution of arene 3(215 mg, 0.5 mmol) in toluene (25 mL). The reaction was stirred for 12hours under an N₂ environment. Concentration in vacuo afforded a crudeoil which was filtered through a 2.5 cm silica plug with 1:1hexanes:EtOAc. Chromatography on silica gel (3:1 hexanes:EtOAc) followedby precipitation with hexanes or ether afforded the desired product (287mg, 87%) as a white, fluffy solid. Recrystallization by diffusion(pentane:CHCl₃) afforded white, needle crystals. Mp: 212-215° C. ¹H NMR(300 MHz, CDCl₃): δ 8.32 (br s, 2H), 8.07 (d, J=4.8 Hz, 2H), 7.74 (br s,2H), 7.47-7.28 (m, 11H), 7.15 (t, J=4.5 Hz, 4H), 6.92 (t, J=4.5 Hz, 2H),1.29 (s, 18H). ¹³C NMR (125 MHz, THF-d₈): δ 152.95, 145.38, 144.62,141.17, 140.40, 138.15, 130.11, 129.56, 128.78, 127.65, 122.94, 120.33,114.49, 110.45, 94.38, 87.33, 35.01, 31.75. Fluorescence emission([11a]≦5.7×10⁻⁵ M in CHCl₃; 371 nm excitation): λ_(max) 411 nm. MS (CIpos) m/z (%): 661 (MH⁺, 49), 660 (M⁺, 100); C₄₃H₄₁N₅O₂ (659.82).

Example 8

This example describes the synthesis of the compound

4-(t-Butyl)phenyl isocyanate (124 mg, 0.72 mmol) was added to a solutionof arene 3 (100 mg, 0.24 mmol) in toluene (10 mL). The reaction wasstirred for 12 hours under an N₂ environment. Concentration in vacuofollowed by chromatography on silica gel (CHCl₃) and trituration withacetone or ether afforded 11b (135 mg, 75%) as a white, fluffy solid.Mp: 197-200° C. ¹H NMR (300 MHz, CDCl₃): δ 8.33 (br s, 2H), 8.05 (d,J=8.7 Hz, 2H), 7.66 (s, 2H), 7.38-7.15 (m, 15H), 1.28 (s, 18H), 1.23 (s,18H). MS (CI pos) m/z (%): 774 (MH⁺+1, 13), 773 (MH⁺, 66), 772 (M⁺,100); C₅₁H₅₇N₅O₂ (772.03).

Example 9

This example describes the synthesis of thiol-based receptors via thescheme:

With continued reference to the scheme above, synthesis began withpreviously reported iodoaniline 4, (Wan, W. B.; Haley, M. M. J. Org.Chem. 2001, 66, 3893-3901) available in 73% yield via iodination oftert-butylaniline. Pd-catalyzed cross-coupling (Metal-CatalyzedCross-Coupling Reactions, 2nd ed.; de Meijere, A., Diederich, F., Eds.;Wiley-VCH: Weinheim, 2004) of 4 with TMSA afforded ethynylarene 5 in 86%yield. Arene 6 was obtained in 79% yield by desilylation of 5 with weakbase (Protecting Groups in Organic Synthesis, 3rd ed.; Greene, T. W.;Wuts, P. G. M., Eds.; Wiley-VCH: New York, 1999; pp 654-657) followed bytwo-fold cross-coupling to 2,6-dibromopyridine. Treatment of diamine 6with an excess of chloroacetylchloride in CH₂Cl₂ afforded diamide 7 invery good yield. Reaction of arene 7 with potassium thioacetate in DMF(van Bommel, K. J. C.; de Jong, M. R.; Metselaar, G. A.; Verboom, W.;Huskens, J.; Hulst, R.; Kooijman, H.; Spek, A. L.; Reinhoudt, D. N.Chem. Eur. J. 2001, 7, 3603-3615) resulted in acetyl-protected receptor8. Crystals of arene 8 suitable for single crystal X-ray diffraction,obtained from slow diffusion of hexanes into a concentrated solution of8 in EtOAc, indicated a dimeric association with intermolecularH-bonding. Treatment of 8 with K₂CO₃ in MeOH and THF under both air-freeand ambient conditions afforded the intramolecular disulfide analog 10in 77% yield instead of the free thiol 9. The disulfide bond of 10enforces a pre-organization of the phenylacetylene substituents with theamide-N, disulfide linkage, and pyridine-N in a potential bindingcavity.

An alternate synthetic route for receptor 9 was investigated followingthe scheme:

Successive treatment of iodoarene 4 with chloroacetylchloride andpotassium thioacetate afforded intermediate 11. Pd-catalyzedcross-coupling of 11 to 2,6-diethynylpyridine (Dana, B. H.; Robinson, B.H.; Simpson, J. J. Organomet. Chem. 2002, 648, 251-269) producedpenultimate 8 in very low yield (5%) due to competitive formation ofbenzothiazinone 12 from iodoarene 11. Both slow addition of thediethynylpyridine to a solution of 11 as well as direct combination ofthe two starting materials resulted in similar product distribution,with 12 as the major product. Benzothiazinone formation can berationalized by pyridine base or metal catalyst deprotection of thethiol moiety followed by nucleophilic displacement of the iodide, aprearranged and favorable formation of an unsaturated six-membered ring.Conversion of 11 to 12 effectively prevented further cross coupling tothe central pyridine core and hence resulted in low yield for arene 8.The remainder of the product distribution could not be discerned butlikely included disulfide and/or oligomeric analogs of both 10 and 11.

Absorption and emission data: Compounds 6-8 and 10 are fluorescentchromophores that exhibit blue or purple fluorescence under UV light(365 nm). The absorption spectra of compounds 6-8 and 10 are dominatedby a characteristic pattern consisting of three peaks. There is a lackof significant spectral changes associated with conversion of diamide 8to disulfide 10, which is not unexpected, as overall conjugation remainslimited by the methylene spacer. Upon addition of TFA, 10 displayedenhanced low energy absorption (>100 nm) as well as conversion from acolorless solution with purple fluorescence to a deep yellow solutionwith yellow fluorescence. Treatment of the acidic solution with aqueousbase resulted in return of the original absorption spectrum andfluorescence of 10.

Example 10

This example describes the synthesis and characterization of4-tert-Butyl-2-(2-trimethylsilylethynyl)aniline 14 via the scheme:

A suspension consisting of 4-tent-butyl-2-iodoaniline 13 (800 mg, 2.9mmol), Pd(PPh₃)₄ (168 mg, 0.15 mmol), and CuI (55 mg, 0.29 mmol) ini-Pr₂NH (50 mL) and THF (50 mL) was degassed by bubbling Ar. TMSA (1.3mL, 9 mmol) was added and the suspension was stirred at room temperaturefor 12 hours under N₂. The suspension was filtered and the insolublesalts washed twice with Et₂O. The filtrate was combined with the Et₂Owashes, concentrated, and purified by Chromatotron (3:2 hexanes:CH₂Cl₂)to afford 14 (611 mg, 86%) as a red-brown oil. ¹H NMR (300 MHz, CDCl₃):δ 7.32 (d, J=2.1 Hz, 1H), 7.17 (dd, J=8.4, 2.1 Hz, 1H), 6.65 (d, J=8.4Hz, 1H), 4.13 (br s, 2H), 1.27 (s, 9H), 0.29 (s, 9H). ¹³C NMR (75 MHz,CDCl₃): δ 145.87, 140.55, 128.68, 127.21, 114.09, 107.25, 102.40, 98.99,33.79, 31.33, 0.16. IR (neat) v 3476, 3381, 2960, 2868, 2147, 1500 cm⁻¹.MS (CI pos) m/z (%): 316 (M⁺+THF, 38), 279 (M⁺+Na⁺, 35), 247 (M⁺+2, 23),246 (MH⁺, 100); C₁₅H₂₃NSi (245.44).

Example 11

This example describes the synthesis and characterization of thecompound referred to above as arene 3:

A suspension of ethynylarene 14 (206 mg, 0.84 mmol) and K₂CO₃ (5 equiv.)in MeOH (20 mL) and Et₂O (10 mL) was stirred at room temperature andmonitored by TLC until completion (15-30 min). The solution was dilutedwith Et₂O and washed with water and brine. The organic layer was driedover MgSO₄ and concentrated in vacuo. Without further purification, theresidue was dissolved in THF (10 mL) and added dropwise over a period of12 hours to a stirred, deoxygenated suspension of 2,6-dibromopyridine(50 mg, 0.21 mmol), Pd(PPh₃)₄ (25 mg, 0.02 mmol), and CuI (8 mg, 0.04mmol) in THF (50 mL) and i-Pr₂NH (50 mL) at 45° C. After an additional 3hours of stirring, the suspension was filtered and the insoluble saltswashed twice with Et₂O. The filtrate was combined with the Et₂O washes,concentrated, and purified by Chromatotron (3:2 hexanes:EtOAc) to afford3 (70 mg, 79%) as a pale brown, crystalline solid. Mp: 226° C. ¹H NMR(300 MHz, CDCl₃): δ 7.64 (t, J=8.1 Hz, 1H), 7.45-7.43 (m, 4H), 7.20 (dd,J=8.7, 1.8 Hz, 2H), 6.67 (d, J=8.7 Hz, 2H), 4.35 (br s, 4H), 1.27 (s,18H). ¹³C NMR (75 MHz, CDCl₃): δ 146.31, 143.84, 140.56, 136.36, 129.24,128.04, 125.73, 114.34, 105.82, 93.11, 87.59, 33.85, 31.31. IR (neat) v3451, 3355, 2957, 2866, 2199, 1500 cm⁻¹. UV/vis (CH₂Cl₂): λ_(max) (ε)249 (44,200), 295 (24,300), 359 (22,500) nm. MS (CI pos) m/z (%): 423(M⁺+2, 100), 422 (MH⁺, 100); C₂₉H₃₁N₃ (421.58).

Example 12

This example describes the synthesis and characterization of thecompound referred to above as arene 7:

A solution of chloroacetylchloride (571 mg, 5.1 mmol) in CH₂Cl₂ (10 mL)was added to a stirred, deoxygenated solution of arene 3 (395 mg, 0.94mmol) and Et₃N (379 mg, 3.76 mmol) in CH₂Cl₂ (10 mL). The reaction wasstirred for 12 hours at room temperature under N₂ and then concentratedin vacuo. CH₂Cl₂ was added and the organic layer was washed thrice withwater, dried over MgSO₄, and concentrated in vacuo. The crude materialwas filtered through a 2.5 cm silica plug (1:1 hexanes:EtOAc) andconcentrated to afford 4 (476 mg, 89%) as a pale brown solid. Mp: 193°C. ¹H NMR (300 MHz, CDCl₃): δ 9.23 (br s, 2H), 8.30 (d, J=8.3 Hz, 2H),7.72 (t, J=8.3 Hz, 1H), 7.64 (d, J=2.1 Hz, 2H), 7.52 (d, J=8.1 Hz, 2H),7.43 (dd, J=8.1, 2.1 Hz, 2H), 4.27 (s, 4H), 1.31 (s, 18H). ¹³C NMR (75MHz, CDCl₃): δ 163.62, 147.46, 143.19, 136.83, 135.83, 129.32, 127.87,126.20, 119.07, 111.15, 94.78, 84.80, 43.21, 34.41, 31.10. IR (neat) v3363, 2962, 2868, 2207, 1691, 1523 cm⁻¹. UV/vis (CH₂Cl₂): λ_(max) (ε)254 (52,600), 293 (27,700), 335 (27,600) nm. MS (CI pos) m/z (%): 578(M⁺+, 15), 577 (M⁺+3, 23), 576 (M⁺+2, 75), 575 (MH⁺, 38), 574 (M⁺, 100);C₃₃H₃₃Cl₂N₃O₂ (574.54).

Example 13

This example describes the synthesis and characterization of thecompound referred to above as arene 8:

Potassium thioacetate (16 mg, 0.14 mmol) was added to a stirred,deoxygenated solution of arene 7 (34 mg, 0.06 mmol) in DMF (3 mL). Thereaction was stirred for 12 hours at room temperature under N₂ and thenconcentrated in vacuo. The crude material was filtered through a 2.5 cmsilica plug (1:1 hexanes:EtOAc) and purified via Chromatotron (2:1hexanes: EtOAc) to afford 8 (35 mg, 92%) as a spongy light yellow solid.Recrystallization by diffusion (hexanes:EtOAc) afforded colorlesscrystals. Mp: 94° C. ¹H NMR (300 MHz, CDCl₃): δ 8.75 (br s, 2H), 8.28(d, J=8.7 Hz, 2H), 7.75 (s, 3H), 7.58 (d, J=2.4 Hz, 2H), 7.39 (dd,J=8.7, 2.4 Hz, 2H), 3.76 (s, 4H), 2.34 (s, 6H), 1.28 (s, 18H). ¹³C NMR(75 MHz, CDCl₃): δ 195.20, 166.16, 146.81, 143.31, 136.59, 136.54,129.38, 127.68, 126.57, 119.45, 110.79, 94.31, 85.15, 34.27, 33.99,31.05, 30.13. IR (neat) v 3339, 3058, 2962, 2868, 2208, 1693, 1518 cm⁻¹.UV/vis (CH₂Cl₂): λ_(max) (ε) 253 (48,200), 291 (24,500), 330 (21,600)nm. MS (CI pos) m/z (%): 656 (M⁺+2, 19), 655 (MH⁺, 44), 654 (M⁺, 100);C₃₇H₃₉N₃O₄S₂ (653.85).

Example 14

This example describes the synthesis and characterization of thecompound referred to above as disulfide 10.

K₂CO₃ (3 equiv) was added to a deoxygenated solution of 8 (23 mg, 0.03mmol) in MeOH (5 mL) and THF (3 mL). The suspension was stirred at roomtemperature under N₂ for 30 minutes and completion was monitored by TLC.Et₂O was added and the reaction mixture was washed with water and/or asaturated solution of NH₄Cl. The aqueous layer was further washed withEt₂O twice. The organics were combined and dried over MgSO₄.Concentration and purification via Chromatotron (3:2 hexanes:EtOAc)afforded 10 (17 mg, 77%) as a crystalline, white solid. Mp: 247° C. ¹HNMR (300 MHz, CDCl₃): δ 9.79 (br s, 2H), 8.47 (d, J=9 Hz, 2H), 7.72 (t,J=7.7 Hz, 1H), 7.57 (d, J=2.1 Hz, 2H), 7.51 (d, J=8.1 Hz, 2H), 7.46 (dd,J=8.8, 2.1 Hz, 2H), 3.70 (s, 4H), 1.58 (s, 2H), 1.34 (s, 18H). IR (neat)v 3318, 2959, 2925, 2855, 2207, 1687, 1515 cm⁻¹. UV/vis (CH₂Cl₂):λ_(max) (ε) 254 (52,200), 296 (24,800), 323 (17,800), 337 (17,500) nm.MS (CI pos) m/z (%): 570 (M⁺+1, 19), 569 (MH⁺, 38), 568 (M⁺, 100);C₃₃H₃₃N₃O₂S₂ (567.76).

Alternate route product, benzothiazinone 12

had the spectral data ¹H NMR (300 MHz, CDCl₃): δ 7.30 (d, J=1.2 Hz, 1H),7.18 (dd, J=4.8, 1.2 Hz, 1H), 6.82 (d, J=4.8 Hz, 1H), 3.43 (s, 2H), 1.29(s, 9H). MS (CI pos) m/z (%): 279 (M⁺+H₂O+CH₃CN, 100), 263 (M³⁰+CH₃CN,73), 218 (M⁺−3, 61); C₁₂H₁₅NOS (221.32).

Example 15

This example describes the synthesis of host compounds according to thescheme:

A suspension of ethynylarene 14 (391 mg, 1.6 mmol) and K₂CO₃ (5 equiv.)in MeOH (20 mL) and Et₂O (10 mL) was stirred at room temperature andmonitored by TLC until completion (15-30 minutes). The solution wasdiluted with Et₂O and washed with water and brine. The organic layer wasdried over MgSO₄ and concentrated in vacuo. Without furtherpurification, the residue was dissolved in THF (10 mL) and addeddropwise over a period of 12 hours to a stirred, deoxygenated suspensionof 6,6′-dibromo-2,2′-dipyridyl (200 mg, 0.64 mmol), Pd(PPh₃)₄ (173 mg,0.2 mmol), and CuI (60 mg, 0.3 mmol) in THF (100 mL) and i-Pr₂NH (100mL) at 50° C. After an additional 3 hours of stirring, the suspensionwas concentrated and filtered through a 2.5 cm silica plug (1:1hexanes:EtOAc). Purification by column chromatography (CH₂Cl₂) afforded15 (159 mg, 50%) as a bright yellow, crystalline solid. ¹H NMR (300 MHz,CDCl₃): δ 8.45 (d, J=7.2 Hz, 2H), 7.81 (t, J=8.1 Hz, 2H), 7.55 (d, J=8.1Hz, 2H), 7.48 (d, J=2.3 Hz, 2H), 7.22 (dd, J=8.4, 2.3 Hz, 2H), 6.70 (d,J=8.4 Hz, 2H), 4.29 (br s, 4H), 1.30 (s, 18H).

Arene 15 (25 mg, 0.05 mmol) was reacted with p-toluenesulfonyl chlorideaccording to General Preparation of Sulfonamides. Chromatography onsilica gel (3:1 hexanes:EtOAc) afforded 16 (38 mg, 96%) as a pale yellowsolid. Recrystallization by diffusion (hexanes:EtOAc) afforded colorlesscrystals. Mp: 251-252° C. ¹H NMR (300 MHz, CDCl₃): δ 8.58 (d, J=7.8 Hz,2H), 7.90 (t, J=7.8 Hz, 2H), 7.77 (d, J=8.4 Hz, 4H), 7.58-7.42 (m, 8H),7.37 (dd, J=8.8, 2.4 Hz, 2H), 7.14 (d, J=7.8 Hz, 4H), 2.32 (s, 6H), 1.29(s, 18H). ¹³C NMR (125 MHz, CDCl₃): δ 155.86, 147.77, 143.85, 141.95,137.44, 136.36, 135.74, 129.54, 129.18, 127.75, 127.40, 127.29, 121.15,120.63, 113.34, 94.77, 84.26, 34.40, 31.13, 21.52. Fluorescence emission([16]≦5.7×10⁻⁵ M in CHCl₃; 343 nm excitation): λ_(max) 390 nm. MS (CIpos) m/z (%): 809 (M⁺+2, 29), 808 (MH⁺, 63), 807 (M⁺, 100); C₄₈H₄₆N₄O₄S₂(807.03).

Example 16

This example describes the synthesis of host compounds according to thescheme:

A suspension of ethynylarene 14 (500 mg, 2 mmol) and K₂CO₃ in MeOH (20mL) and Et₂O (10 mL) was stirred at room temperature and monitored byTLC until completion (15-30 minutes). The solution was diluted with Et₂Oand washed with water and brine. The organic layer was dried over MgSO₄and concentrated in vacuo. Without further purification, the residue wasdissolved in THF (10 mL) and added dropwise over a period of 12 hours toa stirred, deoxygenated suspension of 2,5-dibromothiophene (225 mg, 0.93mmol), Pd(PPh₃)₄ (231 mg, 0.2 mmol), and CuI (76 mg, 0.4 mmol) in THF(50 mL) and i-Pr₂NH (50 mL) at 45° C. After an additional 3 hours ofstirring, the suspension was concentrated and filtered through a 2.5 cmsilica plug (CH₂Cl₂). Purification by column chromatography (CH₂Cl₂)afforded 17 (297 mg, 75%) as a bright yellow, crystalline solid. ¹H NMR(300 MHz, CDCl₃): δ 7.37 (d, J=2.1 Hz, 2H), 7.21 (dd, J=8.5, 2.1 Hz,2H), 7.15 (s, 2H), 6.68 (d, J=8.5 Hz, 2H), 4.16 (br s, 4H), 1.29 (s,18H). ¹³C NMR (75 MHz, CDCl₃): δ 145.52, 140.92, 131.49, 128.62, 127.63,124.52, 114.38, 106.67, 91.25, 86.75, 33.89, 31.33. MS (CI pos) m/z (%):498 (M⁺+2+THF, 18), 497 (MH⁺+THF, 100), 428 (M⁺+2, 18), 427 (MH⁺, 53);C₂₈H₃₀N₂S (426.21).

A solution of arene 17 (90 mg, 0.2 mmol) was reacted withp-toluenesulfonyl chloride according to General Preparation ofSulfonamides. Chromatography on silica gel (CH₂Cl₂) afforded 18 (123 mg,82%) as a pale yellow solid. Mp: 89-91° C. ¹H NMR (300 MHz, CDCl₃): δ7.68 (d, J=8.7 Hz, 4H), 7.54 (d, J=8.4 Hz, 2H), 7.39-7.34 (m, 4H), 7.22(d, J=8.7 Hz, 4H), 7.16 (s, 2H), 7.03 (s, 2H), 2.38 (s, 6H), 1.28 (s,18H). ¹³C NMR (75 MHz, CDCl₃): δ 147.99, 144.00, 136.21, 134.96, 132.48,129.66, 128.98, 127.63, 127.20, 124.09, 120.98, 113.79, 89,54, 87.36,34.39, 31.10, 21.58. UV/vis (CH₂Cl₂): λ_(max) (ε) 234 (58,000), 287(31,000), 330 (27,600) nm. Fluorescence emission ([18]≦5.7×10⁻⁵ M inCHCl₃; 289 nm excitation): λ_(max) 424 nm. MS (CI pos) m/z (%): 807(M⁺+2+THF, 16), 806 (MH⁺+THF, 38), 805 (M⁺+THF, 63), 737 (M⁺+2, 21), 736(MH⁺, 37), 735 (M⁺, 71), 595 (100), 580 (89); C₄₂H₄₂N₂O₄S₃ (734.99).

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope and spirit ofthese claims.

1. A compound or salt thereof comprising the formula

wherein Y represents an optionally substituted aromatic group; n is 1 or2; R is H or lower alkyl; R¹ is H, lower alkyl or aralkyl; R² isselected from H, acyl aralkyl, phosphonyl, —SO₂R³, —(R⁴)C(O)R⁵;—N(R⁶)C(O)OR⁷, and —N(R⁸)C(O)NR⁹R¹⁰; R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰independently are selected from H, lower alkyl, aralkyl, and aryl;provided that Y is not a pyridyl or bipyridyl.
 2. The compound of claim1 wherein Y comprises a heteroaromatic group.
 3. The compound of claim1, wherein Y is a 5- or 6-membered ring.
 4. The compound of claim 1,wherein Y comprises a polycyclic group.
 5. The compound of claim 1,wherein Y comprises a group selected from pyrazinyl, pyrimidinyl,pyrrole, imidazole, triazole, thiophene, thiazole, furyl, and oxazolyl.6. The compound of claim 1, wherein Y is


7. The compound of claim 1, according to the formula

wherein R is selected from H and lower alkyl; and X is selected from—N(H)SO₂R³, —N(R⁴)C(O)R⁵, —N(R⁶)C(O)OR⁷, and —N(R⁸)C(O)NR⁹R¹⁰; R³, R⁴,R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ independently are selected from H, loweralkyl, aralkyl, and aryl.
 8. The compound of claim 1, according to theformula

wherein X is selected from —N(H)SO₂R³, —N(R⁴)C(O)R⁵, —N(R⁶)C(O)OR⁷, and—N(R⁸)C(O)NR⁹R¹⁰; and R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ independentlyare selected from H, lower alkyl, aralkyl, and aryl.
 9. The compound ofclaim 1, according to the formula

wherein R is lower alkyl; X is halogen, —OR¹¹, alkyl sulfide, nitro,sulfonyl, phosphonyl, phosphate, sulfate, or lower alkyl; and R¹¹ is H,acyl, or optionally substituted lower alkyl.
 10. The compound of claim9, wherein X comprises an alkoxy or alkyl sulfide moiety.
 11. Thecompound of claim 10, wherein X has the formula —OR¹¹ or —SR¹¹ and R isoptionally substituted lower alkyl.
 12. The compound claim 1, having theformula

or
 13. The compound of claim 1, wherein the compound is macrocyclic. 14.A method for binding a ligand, comprising providing a host compoundaccording to claim 1 and exposing the compound to the ligand, therebybinding the ligand.
 15. The method of claim 14, wherein the ligand is anionic ligand.
 16. The method of claim 14, wherein the ligand is ananionic ligand.
 17. The method of claim 16, wherein the host isprotonated.
 18. The method of claim 16, wherein the ligand is chloride,sulfate, hydrogen sulfate, perchlorate, pertechnetate, or nitrate. 19.The method of claim 14, wherein the ligand is an inorganic ligand. 20.The method of claim 14, wherein the ligand comprises a metal selectedfrom the group consisting of Pb, As, Zn, U, Ca, Cd, Hg, and combinationsthereof.
 21. The method of claim 14, wherein binding the ligand inducesa change in the fluorescence emission spectrum of the host compound. 22.The method of claim 14, wherein binding the ligand occurs in astoichiometry of about two host compound molecules per ligand.
 23. Acrystalline complex comprising a compound of claim
 1. 24. A method forpreparing a host compound, comprising: providing a compound of theformula

and converting it to a compound of the formula


25. The method of claim 24, comprising providing a compound of theformula

and converting it to a compound of the formula